29 U.S. Scientists Praise Iran Nuclear Deal in Letter to Obama

Twenty-nine of the nation’s top scientists — including Nobel laureates, veteran makers of nuclear arms and former White House science advisers — wrote to President Obama on Saturday to praise the Iran deal, calling it innovative and stringent.

The letter, from some of the world’s most knowledgeable experts in the fields of nuclear weapons and arms control, arrives as Mr. Obama is lobbying Congress, the American public and the nation’s allies to support the agreement.

The two-page letter may give the White House arguments a boost after the blow Mr. Obama suffered on Thursday when Senator Chuck Schumer of New York, a Democrat and among the most influential Jewish voices in Congress, announced he would oppose the deal, which calls for Iran to curb its nuclear program and allow inspections in return for an end to international oil and financial sanctions.

The first signature on the letter is from Richard L. Garwin, a physicist who helped design the world’s first hydrogen bomb and has long advised Washington on nuclear weapons and arms control. He is among the last living physicists who helped usher in the nuclear age.

Also signing is Siegfried S. Hecker, a Stanford professor who, from 1986 to 1997, directed the Los Alamos weapons laboratory in New Mexico, the birthplace of the bomb. The facility produced designs for most of the arms now in the nation’s nuclear arsenal.

Other prominent signatories include Freeman Dyson of Princeton, Sidney Drell of Stanford and Rush D. Holt, a physicist and former member of Congress who now leads the American Association for the Advancement of Science, the world’s largest general scientific society.

Most of the 29 who signed the letter are physicists, and many of them have held what the government calls Q clearances — granting access to a special category of secret information that bears on the design of nuclear arms and is considered equivalent to the military’s top secret security clearance.

Many of them have advised Congress, the White House or federal agencies over the decades. For instance, Frank von Hippel, a Princeton physicist, served as assistant director for national security in the White House Office of Science and Technology Policy during the Clinton administration.

The six Nobel laureates who signed are Philip W. Anderson of Princeton University; Leon N. Cooper of Brown University; Sheldon L. Glashow of Boston University; David Gross of the University of California, Santa Barbara; Burton Richter of Stanford University; and Frank Wilczek of the Massachusetts Institute of Technology.

The letter uses the words “innovative” and “stringent” more than a half-dozen times, saying, for instance, that the Iran accord has “more stringent constraints than any previously negotiated nonproliferation framework.”

“We congratulate you and your team,” the letter says in its opening to Mr. Obama, adding that the Iran deal “will advance the cause of peace and security in the Middle East and can serve as a guidepost for future nonproliferation agreements.”

In a technical judgment that seemed more ominous than some other assessments of Tehran’s nuclear capability, the letter says that Iran, before curbing its nuclear program during the long negotiations, was “only a few weeks” away from having fuel for nuclear weapons.

Dr. Garwin and Dr. Holt were the main organizers behind the group that wrote and signed the letter, according to two of the letter’s signatories. The letter comes amid a flurry of organized efforts by supporters and opponents of the agreement to shape the public debate ahead of congressional action on the deal.

The body of the letter praises the technical features of the Iran accord and offers tacit rebuttals to recent criticisms on such issues as verification and provisions for investigating what specialists see as evidence of Iran’s past research on nuclear arms.

It also focuses on whether Iran could use the accord as diplomatic cover to pursue nuclear weapons in secret.

The deal’s plan for resolving disputes, the letter says, greatly mitigates “concerns about clandestine activities.” It hails the 24-day cap on Iranian delays to site investigations as “unprecedented,” adding that the agreement “will allow effective challenge inspection for the suspected activities of greatest concern.”

It also welcomes as without precedent the deal’s explicit banning of research on nuclear weapons “rather than only their manufacture,” as established in the 1968 Non-Proliferation Treaty, the top arms-control agreement of the nuclear age.

The letter notes criticism that the Iran accord, after 10 years, will let Tehran potentially develop nuclear arms without constraint. “In contrast,” it says, “we find that the deal includes important long-term verification procedures that last until 2040, and others that last indefinitely.”

Correction:

An article on Sunday about a letter of support for President Obama’s proposed Iran nuclear deal written by experts in nuclear weapons and arms control omitted a Nobel laureate from a listing of those who signed the letter. He is Philip W. Anderson of Princeton University.

A version of this article appears in print on , on Page A8 of the New York edition with the headline: Scientists Support Iran Deal in Letter to Obama. Order Reprints | Today’s Paper | Subscribe